Wheat rose for the first day in three in Chicago amid renewed concern that China, the largest producer, may increase imports because of a drought.

Wheat crops in a drought-hit area in China are likely to decline without adequate rain, according to a Bloomberg News survey of five farmers in the southern Jining region of Shandong province, the country's second-largest grower.

"China may have to import more as drought lowers production," Gu Jiong, an analyst at commodity broker Yutaka Shoji Co., said by phone from Tokyo today. "Demand remains strong," he said.

Eoin Treacy's view China seeded clouds to produce some rain and snow on Monday, in an effort to influence weather patterns and to break the drought. It is unclear to what extent such measures are likely to be successful but China is but one player in the global agriculture market. Following an impressive few weeks for food commodities, I thought it may be useful to look at some of medium-term charts.

Wheat was the early leader among food commodities and broke successfully back above 800¢ in January. It pulled back from the 900¢ area earlier this week but a sustained move below 800¢ would be required to begin to question the medium-term uptrend.

Soybeans has paused in the region of 1400¢ and while the pullback earlier this week was reasonably sharp, it has held the majority of its advance and the remains within its six-week range. A sustained move below 1350¢ would be required to indicate that a swifter process of mean reversion is under way.

Corn continues to rally towards its 2008 peak near 800¢ and while becoming increasingly overextended relative to the 200-day MA, a break of the progression of rising reaction lows, currently near 630¢ would be required to indicate the onset of a reversionary pullback towards the mean.

Oats broke out a two-year base in September and quickly rallied to almost 400¢. It has since ranged with an upward bias and a break of the progression of rising reaction lows, near 375¢, would be required to question the consistency of the advance.

Rough Rice has been a laggard among the food grains and encountered resistance near the psychological $16 level last week. It has since pulled back sharply, but steadied near $14.50. Rough Rice is unlikely to decline significantly on its own and the foods complex remains firm which suggests potential for a rebound from near current levels.